TCP/IP Filtering is a “cheap” way to close off or open up certain ports to the outside world. Filtering was never meant to be an all-encompasing security approach, and should never be treated as such. It is an often overlooked but extremely easy security measure to implement. A couple notes of caution when using TCP/IP Filtering:
1. It applies to ALL network adapters on the computer, so adjust accordingly. If you have two adapters and they both need certain ports open/closed, the filtering policy will be applied to both.
2. You will need to restart your computer when changes are applied. In a server environment, sometimes this is an issue.
Start Menu –> Control Panel –> Network and Internet Connections –> Right-Click (on the Adapter you want) and select Properties
The Following Properties box comes up: Select Internet Protocol (TCP/IP) and select Properties.
Select Advanced under the General Tab in TCP/IP Properties.
Under the Advanced Settings, select the Options tab, select TCP/IP filtering and select Properties.
In the TCP/IP Filtering dialog box, check Enable TCP/IP Filtering (All Adapters) and select Permit Only under TCP Ports or UDP Ports depending on your particular needs. Click here for a list of common ports and their uses.